1. Field of the Invention
The present invention relates to an ophthalmologic photographing apparatus that records an image while allowing observing a subject's eye.
2. Description of the Related Art
A fundus camera that photographs the fundus of the subject's eye has widely been known as an ophthalmologic photographing apparatus. There has been known a fundus camera having a plurality of photographing modes for observing the subject's eye and making a photograph according to the purpose of an inspection, including a color photography, fluorescence angiography (FAG) (visible photofluorography), indocyanine green (ICG) (near-infrared photofluorography), etc.
In the photography by the fundus camera, the operation distance between the subject's eye and the fundus camera is to minutely be adjusted. Therefore, an alignment index is projected on the subject's eye, and the alignment adjustment is carried out with the use of the index image. Japanese Patent Application Laid-Open No. 9-131316 discusses that, to distinguish the alignment index from a flare, a plurality of alignment indexes are projected on the subject's eye, wherein each of these indexes is set to have a different brightness, or each of these indexes is flashed with a different cycle or different phase.
The photofluorography such as FAG or ICG is utilized to find a lesion region of the fundus by examining the circulating condition of blood in fundus blood vessels. In the photofluorography, the fluorescent fundus image cannot be observed until the fluorescent agent reaches the fundus blood vessels after intravenously administering the fluorescent agent, which is in several seconds to tens of seconds. Therefore, the operation distance between the subject's eye and the fundus camera is adjusted with the use of the alignment index.
In the photofluorography, a diagnosis, in which a moving image after the fluorescent agent is intravenously administered is recorded and the recorded moving image is interpreted, is an effective method. However, in the diagnosis described above, the alignment index recorded on the moving image overlaps the fundus image, with the result that the desired fundus portion cannot be confirmed.
In order to solve the above issue, Japanese Patent No. 3386258 discusses an ophthalmologic photographing apparatus in which an alignment index is projected only in a predetermined time, which is the time until the intravenously administered fluorescent agent reaches the fundus blood vessels, and the alignment index is turned off or dimmed after the lapse of the predetermined time.
However, the ophthalmologic photographing apparatus discussed in Japanese Patent No. 3386258 has a situation that the operation distance between the subject's eye and the fundus camera with the use of the alignment index cannot satisfactorily be adjusted. In the ophthalmologic photographing apparatus discussed in Japanese Patent No. 3386258, the timing at which the fluorescent fundus image can be observed is shifted from the time when the alignment index is projected. Therefore, the alignment index might be imaged when the fluorescent fundus image can be observed.